SPACE Keeping an eye on water use… from space!

As food shortage weighs heavily on the minds of many, several countries recognise the key role irrigation can play in this issue. A team of EU-funded researchers teamed up to assess how the latest satellite imagery can be applied not only to make water use more efficient, but also to boost farming output in the process.

Researchers from Europe, North Africa and North America are using the FORMOSAT-2 satellite to observe two farming regions — the Tensift Plain around Marrakech (Morocco) and the Yaqui Valley in the Mexican state of Sonora — and have identified a series of benefits that can be accrued by local farmers. In these agricultural areas, irrigated cultivation of cereals, fruit trees and vegetables is practised over several thousand square kilometres.

From its vantage point in space, the FORMOSAT-2 satellite offers farmers a unique perspective on farming practices — a perspective that may lead to huge savings in water consumption.

Based on the latest data from the Food and Agriculture Organization of the United Nations (FAO), 2 500 km3 of freshwater is used for agricultural production each year. This figure amounts to 70% of the water resources used by people each year. With the global population continuing to grow at a fast pace, it is essential to optimise the use of water resources and to increase agricultural production in view of the prospect of having to feed 8 billion humans in 2030.

Scientists have been using remote-sensing satellite observations to improve water balance and farming yield assessment on large geographical scales. Geographic information systems (GIS) allow experts to visualise and comprehend data in ways that reveal relationships, patterns and trends on the ground.

Access to the technology of the FORMOSAT-2 satellite has enabled researchers to get detailed and uninterrupted descriptions of crop growth. From this, they are able to understand and improve yield assessments, as well as develop modelling of water transfer between soil, vegetation and atmosphere.

Remote sensing and GIS are useful for improving soil and water conservation. GIS technologies are already assisting planners elsewhere in the world to analyse dams and to prioritise micro-watersheds for conservation measures based on morphometric parameters. They are also in use in the EU where newly accepted Member States are using them to bring their water infrastructures into conformance with EU standards.

The research team is able to demonstrate the potential capabilities of the new imagery technique with its high spatio-temporal resolution. The FORMOSAT-2 satellite possesses a spatial resolution of two metres in black and white, and eight metres in colour mode. Its colour capability allows it to provide specific information for mapping shallow waters, distinguishing between bare earth and vegetation, mapping forests and identifying crops, and making atmospheric corrections.

Their investigation in the wheat growing area of Morocco, for example, showed that evaporation from the plant cover — the principal factor in water loss — could be evaluated with a margin of error of between 10% and 20%. Gain yields could also be estimated to an accuracy of about 25% at parcel scale.

The FORMOSAT-2 satellite, while operated by Taiwan’s National Space Organization (NSPO), was designed in Europe and built by EADS-Astrium. It is the first and only high-resolution satellite with a daily revisit capability. The ability to acquire repeat imagery of an area of interest every day, with the same sensor, from the same angle and under the same lighting conditions, guarantees a timely flow of compatible data.

This latest research was conducted by a team from the Institut de Recherche Pour le Développement (IRD) at the Centre d'Etudes Spatiales de la Biosphere (CESBIO) in Toulouse, France. The work was part of the SudMed and MedMex programmes at IRD-CESBIO, in conjunction with the Faculté des Science Semlalia of Marrakech, the Office Régional de Mise en Valeur Agricole of Haouz (Marocco) and the University and Technological Institute of Sonora (Mexico).

Other financial contributors to the project were the Coopération Universitaire Franco-Marocaine and the French national space programmes, INSU and CNES.